12v MR16 downlights to 240v GU10 - no earth

[Skyhigh]

The downlights in our living room are 'open' downlights (not fire rated), MR16s in parallel with 35w bulbs. Each fitting has its own 12v transformer.

Since some fittings are covered by insulation (single story extension) I plan to swap them out with Aurora UNIF792SN - which can be covered with insulation and use LEDs too.

The new fittings can run with a GU10 connector or with MR16 connector (no earth, transformer needed).

I originally planned to swap them with GU10's as there's more choice but upon checking the existing lighting wiring - it's only 2-core, there's no earth.

The new downlight fittings are not double-insulated either, so earth is required.


I can see my options as:

A) Have someone re-wire with 3 core to introduce earth. Fit lamps as planned with GU10 connector.

B) Keep wiring as-is.
Use new downlights with MR16 connector.
Instructions clearly say not to use earth when using MR16 connector.
See if existing transformer works with LED bulbs OK (if old style), if not replace with LED transformers.

===

I'm leaning towards B as I'd rather not pay for a re-wire unless I'm overlooking something and there's a really good reason why?


Finally - is it common to run the cabling to 12v downlights without earth at all?
I'm aware low voltage installation instructions often say not to use an earth - but surely for future proofing you'd want to keep earth and by-pass it from the light fittings?



Cheers,

 

[ericmark]

There are three extra low voltage systems. PELV must have a protective conductor, FELV can has a protective conductor, SELV must not have a protective conductor. P stands for Protective, F for Functional and S for Separated. FELV is used where the cables run close to LV cables and inductive or capacitive links could result is voltage appearing on the system, SELV is used where the conductors are exposed the two wires spanning the ceiling where you just hang on ones lights.

However the lighting industry seems unable to label and name items correctly with extra low voltage being called low voltage, switch mode power supplies being called transformers, voltage regulated power supplies being called drivers (current regulated are called drivers), bulbs and lamps being swapped around as to meaning and the SELV being called safety extra low voltage instead of separated extra low voltage. So I am a little sceptical as to if when they call it SELV if really SELV or FELV.

There were two reasons for the 12 volt systems. 1) Safety in bathrooms etc. 2) The quartz bulb can have a thicker element, and voltage regulated, so last longer and slightly more efficient in 12 volt versions.

With LED there are some DC 10 ~ 30 volt lamps which are very efficient and also the odd AC lamp but in the main to get approx 3 volt across the LED means the regulation of current with 12 volt can become more expensive than with low voltage if they use pulse width modulated regulators to control the current so in the main the 230 volt versions are more economic to run and better made than the 12 volt versions. Good LED lamps will give out 100 lumen per watt, but cheap ones are down to 60 lumen per watt and both get the A+ rating.

So in the main using GU10 lamp holders instead or GU5.3 is the better option. MR16 means multifaceted reflector 16/8 inch across so both GU10 and GU5.3 lamps are with quartz version MR16 and LED lamps rarely have the reflector so are MR16 compatible not MR16. I have MR16 compatible with E14, E27, GU10 and GU5.3 bases. Also there is nothing to say GU5.3 is 12 volt or GU10 is 230 volt you can get other voltages.

I would personally fit GZ10 as then it will take the GU10 and the special with dimple think called "something 2" after the building regulation which requires non interchangeable lamps in new builds. Personally I have had problems with 12 volt LED lamps only lasting 3 months I will assume they did not like AC. I have not had a single 230 volt LED fail.

 

[RF Lighting]

Can't you just buy some double insulated fittings?

 

[Iggifer]

Is it two-core just to the fitting from the transformer? Or two core to the transformer? If the former, I'd confirm the latter

 

[Skyhigh]

(Thread resurrection, I know, but I've only had chance to get back to this after many other jobs took precedent!)

Having had a good look with the use of a borescope, mirror, camera and torch I've found:
1. It's two-core from the light switch to the downlight fittings, in parallel, carrying 240v.
2. Each downlight has its own 12v transformer (ETM060, 20-60va, SELV equiv) - in fact, here's an image of one: https://img42.com/oVlIa

It's going to be a complete pain to try and re-wire* - so the best option I can see seems to be to simply swap out the downlight fittings and transformers.

Specifically using AU-UNIF792SN (http://auroraclearance.com/downlights/fire-rated/universal/au-unif792.html) and then some dimmable LED drivers.


Anything seem out of place for this method?

Any recommendations for dimmable LED drivers suitable for 5w bulbs *and* to be potentially covered by insulation?


Cheers,


* Only 1/4 of the ceiling has access from above. 1/4 is underneath fitted wardrobes, 1/4 is under a tiled ensuite and shower and the final 1/4 is in a single-storey extension with *no* access to the small loft space aside from taking tiles off the roof. Wires are thoroughly tacked in place on the joists, seemingly glue has been used where they've gone through a joist, and it would be near impossible to negotiate replacing the section of wiring that goes from the main living room into the small extension as it goes under/through a massive boxed in steel. It all screams 'awkward and expensive' for the sake of running 3-core.

 

[winston1]

(Thread resurrection, I know, but I've only had chance to get back to this after many other jobs took precedent!)


2. Each downlight has its own 12v transformer (ETM060, 20-60va, SELV equiv) - in fact, here's an image of one: https://img42.com/oVlIa

That is NOT a transformer. It is a WRONGLY LABELLED pulse width switch mode power supply.

 

[Taylortwocities]

Skyhigh
please ignore Winston's pedantry. He has a bee in his bonnet about a few things. He has not added any value to the thread by throwing this in. (yet again)

Instead, I will try and help you

Having had a good look with the use of a borescope, mirror, camera and torch I've found:
1. It's two-core from the light switch to the downlight fittings, in parallel, carrying 240v.

Anything seem out of place for this method?

The wiring that is carrying the mains voltage must be two core PLUS earth. Are you sure that there isn't an earth core in that cable?
For the wiring to be kosher, there should be an earth connection in that cable, and that would be carried through, looping from fitting to fitting up to the last downlight.

 

[winston1]

Nothing to do with pedantry. To describe it as a transformer is factually wrong.

 

[Taylortwocities]

Please don't start again. If nothing else, it's just plain boring.

 

[Skyhigh]

Skyhigh
please ignore Winston's pedantry. He has a bee in his bonnet about a few things. He has not added any value to the thread by throwing this in. (yet again)

Instead, I will try and help you

The wiring that is carrying the mains voltage must be two core PLUS earth. Are you sure that there isn't an earth core in that cable?
For the wiring to be kosher, there should be an earth connection in that cable, and that would be carried through, looping from fitting to fitting up to the last downlight.

Thanks for the reply! I'll admit that seeing Winston1's reply did put me off (from the forum) somewhat - until I re-checked and saw your response.

---

As bizarre as it may be, it's definitely 2 core (not 2+e) between all the lights. I spent a long time having a very very good look as it seemed odd.
Plus I really wanted it to be 2+e as there's more downlights/devices that use it.

I removed the light switch to try and verify the lack of earth, there's three lots of 2-core cable. One appears to be for the main downlights (this subject), another for some awful floor-LED-lighting, and another cable which disappears off somewhere (no idea). The cables are adjoined in various fashions with one core from each stripped and sleeved as Earth.
It's definitely not one of the cleanest wiring jobs I've seen - just for the switch....the bits of faded market pen on masking tape don't give me confidence either.


Yes, it's rather odd since the 'transformer' is just before each downlight has a 230v input, then it fair to assume the 2-core used to adjoin all the lights is carrying 230v..

I think I'll get someone out to take a look.


(Why it couldn't have been done with 2+e and the earth parked I have no idea. To me using 2+e would be more logical in case anyone wanted to change the lights out in the future. No other downlights in the house are wires like this.)

 

[Taylortwocities]

Thanks for the reply! I'll admit that seeing Winston1's reply did put me off (from the forum) somewhat - until I re-checked and saw your response.

He does seem to have that effect on posters. It's nuts. People come here asking for help and then get abused for not using exactly the right terminology.

 

[winston1]

Thanks for the reply! I'll admit that seeing Winston1's reply did put me off (from the forum) somewhat


Yes, it's rather odd since the 'transformer'

WHY? However it appears you DID NOT learn from your mistake as you are still referring to it as a 'transformer' which it isn't.

 

[winston1]

He does seem to have that effect on posters. It's nuts. People come here asking for help and then get abused for not using exactly the right terminology.

I'm not abusing anyone, just correcting their mistakes. If no one corrects them they will not learn, sometimes some don't learn even when corrected.

 

[Taylortwocities]

If you have an issue over manufacturers labelling their SMPS products as transformers, then PLEASE take your complaint to them.

Just STOP trying to look clever by grinding out on this forum that this box is not a, it's b. What you are doing is not adding any value, as you can see from the response, you are demoralising the honest DIYers who come to us to ask for assistance.

Maybe you need help, or a hobby. Just stop. You just make yourself look stupid.

Maybe BAS was right.

 

[winston1]

If you have an issue over manufacturers labelling their SMPS products as transformers, then PLEASE take your complaint to them.

Just STOP trying to look clever by grinding out on this forum that this box is not a, it's b. What you are doing is not adding any value, as you can see from the response, you are demoralising the honest DIYers who come to us to ask for assistance.

Maybe you need help, or a hobby. Just stop. You just make yourself look stupid.

Maybe BAS was right.

If you want to stick your head in the sand so be it. It is important to use the correct terms, the reason so many people make these mistakes is because no one points them out. I don't need help and I do have hobbies thank you.

Wonder what has happened to BAS. He could be annoying but I respect his rights to express his opinions.